The correct answer is: C. 90°
The no load current in a transformer is the current that flows in the primary winding of a transformer when there is no load connected to the secondary winding. This current is caused by the magnetization of the core of the transformer. The magnetization current lags behind the applied voltage by an angle of 90°.
Option A is incorrect because the no load current in a transformer does not lead the applied voltage.
Option B is incorrect because the no load current in a transformer does not lag the applied voltage by 120°.
Option D is incorrect because the no load current in a transformer does not lag the applied voltage by 75°.